What is EMT Conduit?
EMT (Electrical Metallic Tubing) is a thin-wall galvanized steel raceway, the most common conduit in US commercial wiring, covered by NEC Article 358.
EMT (Electrical Metallic Tubing) is the most common conduit in US commercial and industrial wiring. Thin-wall steel, galvanized for corrosion resistance, easily bent on-site with a hand bender. NEC Article 358 governs its use.
Construction
- Material: Mild steel, hot-dip or electro-galvanized inside and out
- Wall thickness: Approximately 0.042 inch at 1/2" trade size (much thinner than RMC's 0.133")
- Fittings: Set-screw, compression, or raintight compression
- Lengths: 10 ft sticks standard; longer factory runs available
The thin wall is what differentiates EMT from IMC (Intermediate Metal Conduit) and RMC (Rigid Metal Conduit) — same trade sizes, different bore diameters.
Interior cross-section (NEC Table 4)
| Trade size | Interior area in² |
|---|---|
| 1/2" | 0.304 |
| 3/4" | 0.533 |
| 1" | 0.864 |
| 1-1/4" | 1.496 |
| 1-1/2" | 2.036 |
| 2" | 3.356 |
| 2-1/2" | 5.858 |
| 3" | 8.846 |
| 3-1/2" | 11.545 |
| 4" | 14.753 |
These values feed the EMT conduit fill chart — divide allowable fill (40% for 3+ conductors) by your conductor area to get the max count.
Permitted uses (NEC 358.10)
- Concealed and exposed in dry, damp, or wet locations (with appropriate fittings)
- Direct embedded in or contact with concrete (with the right fittings)
- Subject to severe physical damage — not permitted; use IMC or RMC instead
NOT permitted (NEC 358.12)
- Where subject to severe physical damage (use IMC or RMC)
- In cinder fill where subject to permanent moisture (corrosion risk)
- Where conditions of use will damage the conduit (e.g., hot smelters, food acid environments)
EMT vs IMC vs RMC
Three steel conduit families, same trade sizes, different walls:
| Conduit | Wall thickness | 1" interior area |
|---|---|---|
| EMT (thin-wall) | ~0.042" | 0.864 in² |
| IMC (intermediate) | ~0.080" | 0.959 in² |
| RMC (rigid, thick-wall) | ~0.133" | 0.887 in² |
EMT is cheapest and lightest. IMC has the most interior space at the same trade size. RMC is the heaviest and accepts threaded fittings for hazardous (classified) locations.
Bending
EMT is the easiest conduit to bend on-site:
- 1/2" and 3/4" EMT: hand bender (Klein, Greenlee Hickey)
- 1" through 1-1/4": hand bender + leverage or chain bender
- 1-1/2" and larger: mechanical bender (electric or hydraulic)
Maximum bend radius per NEC Table 2 in Chapter 9 — varies by trade size.
Bonding
EMT itself can serve as the equipment grounding conductor (EGC) per NEC 250.118(4), but only if every coupling and connector is electrically continuous and the fittings are listed for grounding. In practice, many installers pull a separate EGC anyway for reliability.